Clinical and radiological outcomes

Patients were assessed clinically with Kujala [25] and International Knee Score (IKS) scores at a minimum 12-month follow-up and radiographically to measure Caton-Deschamps index [26], patella tilt (PT), and patella shift (Figs. 4 and ​and5).5). All CT and radiographic measurements were independently performed by 2 orthopaedic surgeons who were blinded to the patient outcomes, using a commercially available software program (Picture Archiving Communication System; Carestream Health, Rochester, NY). Femoral and femoral-tibial rotation were measured using techniques previously described [15,16,21]. Patella height measured using the Caton-Deschamps index [26] and patella skyline views were taken at an angle of 45°, and from this, PT and PS were measured as described by Merchant et al. [27].

Left total knee arthroplasty with patella dislocation preoperatively. (a) Anteroposterior view. (b) Skyline view showing 37° tilt. (c) Lateral view.